Chairs have been developed having many different designs and constructions. One type of chair uses tubular frame tubing to construct a chair frame. The frame tubing may have upwardly projecting columns which each define a post to which an armrest is mounted. An example of such a chair is U.S. Pat. No. 5,746,479.
It is an object of the invention to provide an improved armrest and in particular, an improved connection between an armrest and a frame tube which defines an anti-rotation connection between the armrest and frame tube and also lockingly engages these components together.
The invention thereby relates to an armrest for a chair wherein the chair is provided with upwardly projecting tubular uprights that are disposed on opposite leftward and rightward sides of a seat. The frame tubes which define the post have a tubular shape with a uniform circular cross-section along the major length thereof. At the upper ends of the frame tube, however, the upper end is shaped and in particular, preferably is swaged, so that the terminal upper end of the frame tube has a non-circular shape.
The frame tube is of a conventional metal tubular construction wherein the shaping or swaging operation results in a shape which facilitates the mechanical connection of the armrest to the frame tube. This non-circular shape is defined by the outer exterior surface of the frame tube, and preferably as a four-lobed shape wherein individual lobes are separated one from the other by channel-like recesses.
The swaged shape of the frame tube also defines a central bore which opens upwardly and is adapted to threadedly receive a downwardly projecting fastener which projects through the armrest and mechanically fastens the armrest to the frame tube. In this regard, the recesses of the swaged tube end have interior surfaces which are arcuate and each define an apex wherein the apexes of each recess are located in four quadrants and provide interior surfaces to which the threads of the fastener can bite or engage. These apexes do not require threading during the manufacturing process but are threaded by a self-tapping screw which is used as the fastener.
As to the armrest, the armrest includes a downward-opening collar which defines a downward-opening socket into which the upper tube end is received. The socket has a non-circular configuration which generally conforms to the swaged tube end so that when the socket is slid onto the tube end, the armrest is prevented from rotating. Further, the innermost end wall defining the bottom of the socket has a fastener bore projecting vertically therethrough in co-axial alignment with the socket and which is adapted to receive the fastener downwardly therethrough. This fastener bore is aligned with the central opening of the tube end wherein the armrest is secured in position by threading the fastener down into the swaged tube end.
This provides a relatively simple connector structure for the armrest and chair frame and allows for easy assembly since the frame tube does not require any additional structures to be added thereto.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.